Process for preparing 1-4-5-8 naphthalene tetracarboxylic acid



Patented Dec. 28,1926.

' UNITED STATES PATENT OF FICE.

wILnELM'ncxERr, or :aOOHsT-ON-TEE-MAIN, ERMANY, AssIe'Non 'ro emissannrDYESTUFFS CORPORATIQN, OF NEW YORK, n. Y., a conrona'rrou.

PROCESS FOR PREPARING 1-4-5-8 NAPHTHALENE TETRACARBOX Y LIG ACID.

NO Drawing.

The 1.4.5.8 naphthalenetetracarboxylic acid has for the first time'loeenprepared by Bamberger and Philip (see Liebigs Annalen vol. 240 page182). from pyrenic acid by oxidation, a. method which, however, offersno technical interest owing to the fact that the said pyrenic acid isscarcely obtainab e.

Furthermore the said acid has been obtained in a very intricate mannerby Freund and Fleischer (see .Liebigs Annalen vol. 373 page 322/24 andvol. 402 page 70/74) by condensing .acenaphthene withdi'ethylmalonylchloride, extracting withether, is0- lating theisomerides formed during this condensation, splitting up theacenaphthene- I diethyl-peri-indandion by boiling with potassiumhydroxide-solution of 50% strength, converting theresulting potassiumsalt of the 4-diethyl-acetyl-1,8-acenaphthene-5-carboxylic acid into itsfree. acid and finally oxidizing the acid.

Now I' have malonylchloride there is -'apparently only formed theperi-acenaphthenindandion of vthe formula:

found that, when using Application filed August 31, 1925. Serial No.53.735.

gradually introduced. The reaction, which sets in vehemently, isadvantageously somewhat moderated by cooling. When the for mation ofhydrogen chloride has ceased, the mass is further heated for a shorttime on the steam bath in order to complete the re-- action. Thepro'duct resulting from the re-' action is decomposed with ice,distilled with steam and directly dissolved in a diluted solution ofsodiumparbonat'e or a caustic soda solution. A solution of 50 parts ofpotasslum permanganate in 1000 parts of wateris added to this alkalineSolution and the whole is heated on the steam bath until decolorationoccurs.- The manganese dioxide is then filtered off and thenaphthalene-1.4.- 5.8-tetracarboxylic acid is precipitated in thefiltrate by means of hydrochloric acid. The structural formulae of theintermediate and final products may he represented as follows:

. t. HAD-0'13, Bee -#0112 I 1) cool H,- +2HCI cooi Hie-03, 1100? 00011(2) oxidizing agent and that this compound can bedirectly oxi' dized byan oxidizing agent to the naphthalene-l11.5.8-tetracarb0xylic acid. I

' This new process represents a considerable simplification which isparticularly due to the surprising ,fact that the indandionring mustnot-be split open in order to permit the oxidation.

The said acid isa useful starting..-inaterial for the manufacture ofdyestufisi In an analogous manner the derivatives of acenaphthene with afree peri position can be converted into the corresponding derivativesof the naphthalenetetraca'rboxylic acid. 'f

The following example illustrates my invention, the arts bein by.weight:

wards 35' parts of chloride are i If a greater excess ofmalonylchlor'ide, for

20 parts 0 acenapht ene are-dissolvedin instance -80 parts andcorrespondingly to 90 parts of aluminium-chloride and about 70 parts ofpotassium permanganate are employed, the yield isessentially greater.

Instead of the carbon-disulfide there may also be used other indiflerentsolvents and instead of potassium permanganate any other oxidizingagent.

I claim: v

Process of producing naphthalene-1.4.5.8- tetracar'boxy'lic acidconsisting in condensing acenaphthene' with a malonylchloride andoxidizing the product of reaction.

In testimony whereof, I afiix my signature.

.1)... ECKERT.

